I did "rails new TravelApp" which works. But installing gems is turning instruction pink.However, all the gems seem to have worked.Also typing "rails", "bundle" or other commands do not give all the arguments

I've actually already answered that for someone else right here - Bundler only works with a specific file, so you don't need to specify it.

it is not clear what to add next

Nothing complicated yet, just type rails s -p 8000 in the terminal to start up the server, then you'll visit the page in the local browser to the right of the terminal. You'll be adding routes in later exercises